The goal of this project is to provide direct quantitative data regarding the microcirculatory effects of several anesthetic drugs during both the normovolemic and hypovolemic states. The microcirculation in the rat cremaster preparation is visualized and the following variables are measured: 1) mean arterial pressure, 2) heart rate, 3) rectal temperature, 4) cremaster muscle temperature, 5) inspired anesthetic concentration, 6) small artery (30-60 microns) diameters, and 7) small vein (30-90 microns) diamerer. Most variables are obtained at 30 second intervals and all data are smoothed, normalized, and averaged using laboratory computer techniques. Important aspects of the study include: 1) comparison of the effects of equipotent anesthetic concentration on microvascular mechanisms, 2)quantitative microcirculatory data obtained during constant levels of anesthesia, and 3) similar observations during constant levels of anesthesia in the hemorrhaged rat. The expected results will form a basis for evaluating the mechanism by which anesthetics alter the microvascular response to hemorrhage and thus alter survival rates following hemorrhagic hypotension. BIBLIOGRAPHIC REFERENCES: Longnecker, D.E.: Circulatory and microvascular responses to nitrous oxide in the rat. Fed Proc 34:771, 1975. Longnecker, D.E.: Effect of anesthetic agent on survival following hemorrhage. Abstracts of Scientific Papers, 1975 ASA Annual Meeting, 245-246, 1975.